Disturbance 94L in Central Atlantic; NHC management changes

A tropical wave midway between Africa and the Lesser Antilles (labeled "invest 94L" by NHC this morning) has become a little better organized this morning, and does have the potential to develop into a tropical depression later this week. Wind shear is a favorable 5-10 knots over 94L, and shear should not be a problem for it over the next few days. The system is not well-organized, with a sloppy, elongated circulation, as seen on last night's QuikSCAT pass. This morning's QuikSCAT pass missed the storm. The system does have a major impediment to development--the presence of a large, dusty area of dry air surrounding its north side (Figure 1). Water vapor satellite loops of the region don't show any significant moistening of the region around 94L occurring, and this will have to happen before the system can develop into a tropical depression. If the storm can develop a better-organized circulation, it will be able to pump more moisture into the surrounding atmosphere and help itself out. Current visible satellite loops shows that this is not happening at present--the thunderstorm activity associated with 94L is rather weak.

None of the reliable computer models develop 94L. The system should track through the Lesser Antilles Islands on Friday, bringing gusty winds and heavy rain. I expect that the earliest 94L could become a tropical depression would be Thursday, and it is unlikely the Lesser Antilles would experience anything worse than a 50 mph tropical storm. It is more likely that 94L will still be a tropical disturbance when it passes through the Lesser Antilles.

Figure 1. Water vapor satellite image of the Central Atlantic from 8:15am EDT 8/28/07. The brown colors denote very dry and dusty air from the Saharan Desert.

Honduras disturbanceA westward-moving tropical wave is bringing heavy rains to Honduras and Nicaragua today. Due to its close proximity to land, development of this wave into a tropical depression is not expected. The wave is under 10-15 knots of wind shear. None of the reliable models are predicting that this system will develop.

Computer model updateThe UKMET and GFS models are indicating the possible development of a tropical depression by Thursday or Friday off the coast of Africa. There is a large surge of moisture with at least one strong tropical wave embedded in it coming off the coast of Africa this week. This moister air should make a more favorable environment for a tropical depression to form in than the one 94L finds itself in.

Most of the models also predict a low pressure system will develop off the North Carolina coast along an old frontal boundary on Thursday. Such a development may be an ordinary extratropical low pressure system, but could make the transition to a tropical system if the shear drops low enough.

NHC management changesActing director Dr. Ed Rappaport of The National Hurricane Center (NHC) will continue on the job until the end of this hurricane season, NOAA management revealed yesterday. Rappaport replaced director Bill Proenza on July 9, following an extraordinary few months of tumult at NHC. Joining the NHC staff on September 4 will be a new interim deputy director--Bill Read, who currently serves as the meteorologist in charge of the National Weather Service's Houston-Galveston office. Deputy director was the post Rappaport held prior to July 9. Bill Read applied for the directorship of NHC when Max Mayfield retired, but was not awarded the job. His arrival at NHC during the peak of hurricane season will be a welcome addition, as he has considerable experience dealing with hurricane emergencies.

In an apparent effort to follow some of the management changes recommended by the independent review team that performed the snap inspection of NHC in early July (see Attachment 9 of the Senate testimony from July), a new manager of the ten hurricane forecasters has been appointed as well. Rick Knabb, who is one of the six senior hurricane specialists, will be the new manager, and will be Rappaport's backup for TV interviews during hurricane emergencies.

It is still undecided where former director Proenza will wind up, but the chairs of two Senate subcommittees investigating the matter have recommended that Proenza be returned to his former job as head the NWS Southern Region.

Next updateTomorrow is the 2-year anniversary of Hurricane Katrina. I'll discuss my experience with blogging about the storm, and give an update on 94L and the rest of the tropics.

Right now 94L is organizing but 94L will need to face high wind shear by 60w ahead. I think that's why the gfs weakens the system and some models don't develops nothing and some models only take it to a tropical storm status. Of course conditions can become more favorable but we need to wait at least 2 days.

I agree with WeatherMSK. My father and I have been discussing how the first frost arrives later than it used to, and how you can harvest tomatoes until the first week of December in N.C. now.

Rememebr Jeff Masters mentioning that the smaller norhtern ice cap could delay the winter. We may need to get out of thinking that hurricane season is mostly September phenominon. Big storms like Wilma in the final week of October may not be as "freak" as they used to be.

Two years ago today ,i spent the day convincing my daughter to leave New Orleans. I was convinced that this was the storm that we had all been talking about because of the information shared on this web site. My thanks goes to all of you and especially Storm Junkie who's passion and information made the difference for me and my family that day. Say a prayer for all who are still healing from that day.

Well I see we now have 95, and as several have noted the Africa wave is looking pretty impressive. I guess there is an outside shot we have three Atlantic named storms before Sept 1st...Crazy how quickly things can change. The QS on 95 looks fairly sloppy right now, but there are some decent winds with it and as it detaches from the front it should be in a better spot for development.

Good morning to you all. The tropics have become active once again after a one week lull from Dean and Erin. I have just updated my website on both Invests. I still have to wait for more reliable computer models before placing them on my site. It appears to me as if both systems may be getting their act in gear and seem to be developing, albeit slowly. To me, Invest 94L has a better chance of development than 95L, but that could always change. They both have increased convection and clear cyclonic turning. We will have to wait for the surface observations and QuikScat on Invest 95L. Well, I'll be here later on today. Take it easy all.

I agree with the season starting later. We all know the specific heat of water and that surface temps will stay warmer later in the year so storms will have a better chance on that front. I also think november could see 2 or even 3 storms.

I live in the Turks and Caicos Islands and I am leaving for Anguilla for a week.So I hope that I will be able to enjoy myself without having to worry rushing home to board up .....yes???

No real need to worry, if the system we're watching does develop it will likely only be a tropical depression or maybe a weak tropical storm. Certainly nothing like Dean. Also if the wave that is currently emerging off Africa develops it will be a while before it affects anybody.